1. Field of the Invention
The present invention relates to pattern recognition devices, and more particularly to recognition systems which distinguish spoken words.
2. Description of the Prior Art
Speech recognition by artificial intelligence has had extensive study and recent developments in this area are both numerous and complex. Along with these developments the understanding of the mechanisms of human speech and the mental functions evolved for the recognition thereof has improved. Nevertheless, complex and difficult patterns and functions are inherent and the increased understanding has not simplified, to any significance, the recognition task.
This difficulty is inherent in the phenomenon of speech. For example, the course of human speech includes variables in the mechanical structure of the voice generating mechanism, i.e., the voice box, which moreover varies from day to day along with the state of health of the person and with the psychological states one goes through. Additionally, the speech patterns uttered by a person vary with the message and with the intent the communicator desires to convey, and may be rushed or slowed down in response to external inputs which a recognition system would have difficulty to perceive.
These and the many other variables of communication, (i.e., concurrent body language) make voice pattern recognition an extremely complex task and the resulting systems are therefore extremely complex and limited.
Unlike human voice recognition the application of artificial recognition systems often involves functions not inherent to humans, like security functions, which modify the architecture of the logic and impose constraints of their own not always compatible with the recognition function. Thus, for example, an artificial recognition system may be structured not to recognize all voice patterns, being responsive to a selected group only. Moreover, limited lexicons are often preferrable to unlimited ones, particularly when security concerns exist.
For all these reasons specialized recognition systems have been sought in the past and it is one such system that is set out herein.